ERBB3 and breast cancer: In accordance with our observations, ErbB2 activation, in concert with ErbB3 and ErbB4, leads to the expression of FABP5, an intracellular lipid binding protein, which plays a crucial role in PPARβ/δ transcriptional activation in the MCF7 cell line, suggesting that the EGFR superfamily could also act upstream of PPARβ/δ to regulate its activity in a model of breast cancer (Kannan-Thulasiraman et al, 2010).